The present embodiments relates generally to a system and methods for controlling or tuning toner concentration through specific toner properties. Specifically, the present embodiments configure the toner shape factor, such as circularity, to easily control or tune toner concentration. The present methods provide a cost efficient way in which to optimize system operation and obtain more robust system.
Electrophotography, which is a method for visualizing image information by forming an electrostatic latent image, is currently employed in various fields. The term “electrostatographic” is generally used interchangeably with the term “electrophotographic.” In general, electrophotography comprises the formation of an electrostatic latent image on a photoreceptor, followed by development of the image with a developer containing a toner, and subsequent transfer of the image onto a transfer material such as paper or a sheet, and fixing the image on the transfer material by utilizing heat, a solvent, pressure and/or the like to obtain a permanent image.
In electrostatographic reproducing apparatuses, including digital, image on image, and contact electrostatic printing apparatuses, a light image of an original to be copied is typically recorded in the form of an electrostatic latent image upon a photosensitive member and the latent image is subsequently rendered visible by the application of electroscopic thermoplastic resin particles and pigment particles, or toner. In a conventional electrophotographic process, a latent image is electrically formed on a photoreceptor containing a photoconductive material using any of various methods. The latent image is developed with a toner, and the toner image on the photoreceptor is transferred, directly or via an intermediate transfer member, to an image-receiving film such as paper. The transferred image is fixed by application of, for example, heat, pressure, heat and pressure, or a solvent vapor. A fixed image is formed through the plural steps described above.
Electrophotographic imaging members may include photosensitive members (photoreceptors) which are commonly utilized in electrophotographic (xerographic) processes, in either a flexible belt or a rigid drum configuration. Other members may include flexible intermediate transfer belts that are seamless or seamed, and usually formed by cutting a rectangular sheet from a web, overlapping opposite ends, and welding the overlapped ends together to form a welded seam. These electrophotographic imaging members comprise a photoconductive layer comprising a single layer or composite layers.
There is a constant desire to improve the characteristics and performance of toner compositions. One area of possible improvement focuses on how the toner is used and interacts with the xerographic system. Optical sensors are known and used in printing systems to detect transferred toner mass amounts through reflectance measurements. For example, U.S. Publication No. 2008/0089708, discloses use of optical reflective-based sensors to generate and compute reflection outputs to determine an amount of toner mass present on the toner application surface.
Toner concentration control in two component development systems is very important for multiple reasons. The interaction between toner and carrier particles in the development housing to a large extent drives charge generation, which is a critical parameter for system performance. Each development subsystem running a specific toner formulation has a unique latitude. If the system operates outside its latitude it can lead to significant variation in density as well as dysfunctions such as background, internal emissions (spits), and bead carryout. In extreme cases this dysfunction can be detected as severe image quality defects such as spots. Thus toner concentration control is maintained through a closed loop control system that monitors the degree to which the toner is developing, and also monitors the changes in the magnetic permittivity of the developer material in the development housing. The effectiveness of the control system, however, can be affected by dysfunctions in the components, including the photoreceptor, Reflection Automatic Density Control (RADC) sensor, Auto Toner Concentration (ATC) sensor, and also the developer material (including the toner) itself.
As such, the present embodiments are directed to a system and methods for controlling toner concentrations through the toner shape factor, and specifically, circularity, to prevent dysfunctions and provide a more robust and optimized xerographic system.